Hi, I have a household w/2 aliens living in it. I currently have them transmuting all the gems and metals they find and I'd like it if I could set only their brain power/energy to static and not the rest of the family. Is that possible?

As this project is only concerning members of one household, I'm not sure why a caste would be necessary. Why not use SP > Sim Options on the sims required? Sim Options will always trump Town, Household, and Caste.